The present invention relates to shell structure of a musical drum and its effect on strength, weight, appearance and tonal qualities and to the means of applying and maintaining correct tension in the members connecting the drum head membranes and shell structure.
Musical drums have traditionally been comprised of a tube or shell with a membrane stretched over one or both ends of the tubular shape. When the membrane surface is made to vibrate by an impact from either the percussionists hand or a hand held specially designed stick, a particular tone is produced peculiar to the dimensions of the shell in combination with the qualities of the membrane. The pitch and properties of the sound produced can be influenced by the toughness of the vibrating membrane.
Early drums that used a membrane on each end of the tubular shell employed cord or rope that was laced between the two animal skin membranes to coincidentally tension these membranes or heads. The ropes eventually gave way to metal tension rods between the upper and lower vibrating heads and metal hoops to mechanically capture the edges of the skin.
The advent of the metal componentry allowed higher levels and more uniform levels of tension to be attained. As the desire for more accurate tensioning of the heads increased, the necessity to anchor the hardware to the shell to isolate the affect from the tensioning of one head over the other became apparent. New materials for the vibrating heads lead the demand for higher and higher tension requirements and consequently higher load requirements on the anchoring bracketry. The bracketry increased in size and then in number in order to spread the loads around the body of the shell.
The introduction of the aramid fiber reinforced batter head put the load requirements at a level that demanded a technology change. No matter how many brackets were employed the component failure was eminent and the weight of the overall instrument was unacceptable to the consumers. Several manufactures employed double contra tightening double hoop tensioning devices to isolate the loads completely from the shell and eliminated the brackets entirely. This tactic proved successful and has been the industry standard to date. However, a consequence of the isolation of the tension loads was a loss of sound quality due to a reduced participation of the shell in the amplification of the impact pulses from the membrane.
Accordingly, there is a need to provide a shell structure of a musical drum that will allow it to withstand the stress and stain loads placed upon it by the tensioning of the vibrating membranes.
Another issue in drum construction is the tensioning of the membranes. A typical musical drum is comprised of a hollow drum shell of cylinder-like shape, open at both ends, one or both openings being covered by a drum head membrane tensioned by means of a moveable ring engaging both membrane and tensioning cables or rods arranged around the periphery of the drum shell. When a different tension is required at each head, the tensioning member must be attached to the shell by protrusions from the shell as shown in U.S. Pat. No. 4,428,272 or to a second ring arranged within the floatable ring and bearing on the inner surface of the membrane as shown in U.S. Pat. No. 4,869,146. As better drum membrane materials allowed higher tensioning, the stresses created at the drum shell by brackets attached directly to the shell caused failures. To avoid failure, the drum shell and hardware had to be made stronger. The protrusions and shell must be made very robustly in order to resist the cantilevered load applied by the tensioning means and the drum is then very much increased in weigh and complexity, is prone to relaxation of the tension and to damage because of the bending nature of the load. These brackets also interrupt the interior of the shell decreasing the sound quality. Several methods have bean devised for avoiding these problems and in the case of U.S Pat. Nos. 4,714,002 and 4,869,146, heavy tie rods attached to rings at opposite ends of the shell avoid interruption of the shell. Use of an added inner drum head ring to react to the moveable tensioning ring loads provides the desired strength but adds to the weight and reduces the shell""s participation and therefore its musical properties.
In order to improve a drum""s musical properties improvements have been made to the uniformity and density of the shell as in U.S. Pat. No. 4,993,304 and to the interior surface as in U.S. Pat. No. 4,356,757 in which an inner cylindrical sleeve, flexibly suspended, is used to isolate the shell structure from the resonant cavity. These improvements are intended to enhance the response of the drum and the purity of the tone. While they do improve musical quality, they do not generally increase robustness or lightness of the shell structure and tensioning members.
The tuning of a drum has always been troublesome and time consuming since the member tension constantly changes with creep, humidity, and temperature. Furthermore, it is necessary to individually readjust the tension of each tension member to the same value.
U.S. Pat. No. 5,427,009 solves the problem of simultaneous adjustment and equal tensioning by the use of hydraulic actuators and a means for providing a pressurized fluid to the actuators but the actuators and means for providing the pressurized fluid to them adds a great deal of cost, bulk and extra weight.
A less complex but non-simultaneous means of correctly setting the tension is disclosed in U.S. Pat. No. 4,287,806 with the use of a torque indicator on each tension rod as a means of determining the amount of tension applied to each tension member. To set tension, the device relies on adjusting screw torque which is generally inexact and it must inconveniently be backed-off in order to reset the tension.
Accordingly, there is also a need to provide an improved structure to tension the membranes of a drum.
An object of the invention is to fulfill the needs referred to above. In accordance with the principles of the present invention, an objective is achieved by providing a drum shell comprising a rigid, hollow body disposed about an axis and having first and second opposing opened ends. The body has an inner surface and an outer surface. The outer surface is of convoluted form.
In accordance with another aspect of the invention, a drum includes a rigid, hollow body disposed about an axis and having first and second opposing opened ends of generally circular form. The body has an inner surface and an outer surface with the outer surface being of convoluted form defined by a plurality of channels formed in the body. The channels extend in a direction of the axis. A drum head membrane covers each of the first and second ends. A ring is mounted on each of the first and second ends so as to secure each drum head membrane to the body. Each ring includes a tensioning member receiving structure. A plurality of tensioning members are provided with a tensioning member being received in an associated channel and a first end of each tensioning member being received by the tensioning member receiving structure of each ring. The tensioning members are constructed and arranged to be moved with respect to the body to adjust tension of the drum head membranes.
Other objects, features and characteristics of the present invention, as well as the methods of operation and the functions of the related elements of the structure, the combination of parts and economics of manufacture will become more apparent upon consideration of the following detailed description and appended claims with reference to the accompanying drawings, all of which form a part of this specification.